In 'ER70S-X', what does 'S' indicate?

In the designation 'ER70S-X', the 'S' indicates that the electrode is solid. In MIG welding, the electrode wire used is often made of solid metal, which is a crucial factor in determining the type of welding application and the properties of the weld.

Solid electrodes are preferred in many applications because they provide a smooth and consistent weld bead, leading to strong and reliable joints. This designation is part of the American Welding Society (AWS) classification, where 'E' stands for electrode, 'R' denotes that it is a filler metal that can also be used in an ER (Electrode Rod) form, '70' indicates the minimum tensile strength of the weld deposit in thousands of psi, and 'S' specifically defines the type of electrode as solid.

The other options refer to different aspects of the welding process or equipment. The 'specific gas mixture' relates to the type of shielding gas that could be used, but it is not indicated by 'S'. 'Submerged arc welding' is a different welding process altogether, and the term 'shielding type' does not fit into the context of the 'S' designation but rather pertains to the type of gas used in conjunction with the electrode.